All locations given below (including the false answers) are places of interest in Varna, so if you have enough time you won't regret visiting them all. It is not required to pay a fee anywhere on the tour in order to find the answers, although you may do so in order to find more about the place.
Your starting point is at the entrance of the city harbour. The coordinates are given at the top of the page. I apologise in advance of the unpleasant state of the final point. I've cleaned it once and haven't got the chance to change it later on.
Stage 1 - The Lighthouse - what colour are the eyes of the saint whose icon is on the lighthouse base?
a) If they are brawn go to N43 12.0850 E27 55.3276
b) If they are green go to N43 12.0030 E27 55.2987
c) If they are blue go to N43 12.0040 E27 55.0500
Stage 2 - The Water - how many meters approximately is the height of the highest ancient building you see?
a) If it is 11 go to N43 12.0660 E27 54.8087
b) If it is 34 go to N43 11.9040 E27 54.7440
c) If it is 18 go to N43 12.2547 E27 54.6119
Stage 3 - The Tower - How many glass windows there are on the tower?
a) If they are 23 go to N43 12.2572 E27 55.4922
b) If they are 19 go to N43 12.4329 E27 54.9642
c) If they are 16 go to N43 12.2234 E27 54.7555
Stage 4 - The Fountain - How many separate pools does the fountain have?
a) If they are 5 go to N43 12.3670 E27 55.1880
b) If they are 6 go to N43 12.6081 E27 54.9301
c) If they are 3 go to N43 12.8201 E27 55.5412
Stage 5 - The Meeting - The statue of which famous person do you see?
a) If it is Mahatma Gandhi go to N43 12.2198 E27 55.3405
b) If it is Winston Churchill go to N43 12.2615 E27 55.0792
c) If it is Napoleon Bonaparte go to N43 12.3864 E27 55.6273
Stage 6 - The Plaque - What are the two years that you see written in front of you?
a) If they are 1860-1915 go to N43 12.5052 E27 55.4371
b) If they are 1880-1945 go to N43 12.3032 E27 55.4943
c) If they are 1860-1945 go to N43 12.5547 E27 55.9553
Stage 7 - The Monument - How many steps lead to the monument?
a) If they are 16 go to the final location at N43 12.7754 E27 56.5965
b) If they are 19 go to the final location at N43 12.7751 E27 56.4781
c) If they are 21 go to the final location at N43 12.4231 E27 56.4292
Get the details of the other caches in Varna so that you can cover at least some of them along the tour. Enjoy.